<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <form name="form1">
        <h2>form1</h2>
        <p>
            <select name="city">
                <option value="nj">南京</option>
                <option value="sh">上海</option>
                <option value="wx" selected>无锡</option>
                <option value="sz">苏州</option>
            </select>
        </p>
    </form>
    <script>

        document.form1.city.oninput = function () {
            console.log('oninput', this.value);
        }

        // document.form1.city.onchange = function () {
        //     console.log('onchange', this.value);
        // }




    </script>
</body>

</html>